Energy resolution values of GAGG:Ce crystals coupled to various SiPMs

Abstract GAGG:Ce (Gadolinium Aluminum Gallium Garnet doped with Cerium) crystals coupled with SiPMs (Silicon Photomultipliers) form a scintillation detector system commonly used in various fields such as medical imaging, high-energy physics, and radiation detection. The purpose of this study is to compare the energy resolution performance of GAGG:Ce crystals coupled to various SiPMs. Comparisons were conducted among crystals and photomultipliers from various companies, all featuring a pixel size of 3 × 3 mm 2 . The detector system consisted of a crystal optically coupled to a SiPM array, along with the photomultiplier electronics. The entire system was housed within a black box, positioned adjacent to a radiation source—a closed-type 137 Cs isotope, intended for laboratory use—with a radioactivity value of 0.03 MBq. All crystals underwent surface polishing and were subsequently wrapped with multiple layers of Teflon. Additionally, an optical grease was applied between the crystal and the photomultiplier to enhance their optical properties. The size of the crystals and their coupling with the SiPMs were found to significantly impact the energy resolution. Excellent energy resolution values, up to 4.9%, were achieved for the majority of the crystals and SiPMs. Utilizing the 30035 C-Series SiPM from Onsemi, GAGG-HR single crystals exhibited the most favorable energy resolution values, achieving 5% for both 3 × 3 × 5 mm 3 and 3 × 3 × 8 mm 3 sizes. Furukawa GAGG:Ce crystals demonstrated consistent energy resolution ranging from 6.6% to 7.2%. Employing the PM3350 Trench type SiPM by Ketek, GAGG-HR single crystals achieved the best energy resolution values of 5.5% for 3 × 3 × 5 mm 3 and 5.7% for 3 × 3 × 8 mm 3 sizes. Furukawa GAGG:Ce samples of 3 × 3 × 5 mm 3 crystals yielded an energy resolution value of 6.8%. When using the S10362-33 Series SiPM from Hamamatsu, the best energy resolution values were obtained with the S10362-33-050 SiPM coupled with 3 × 3 × 8 mm 3 GAGG:HR crystals, resulting in an energy resolution of 8%.